Antibodies to various kinds of collagen will be searched for in rheumatoid arthritis patients and in various controlled conditions (Normals and patients with other forms of arthritis and other chronic diseases). The significance of these antibodies will be ascertained: namely, whether they are cause, effect, or merely serologic markers indicating genetic predisposition to development of RA. Patients and their families will also be typed for the newly discovered IgM allotypic markers, since typical rheumatoid factors are IgM.